Current oscillometric blood pressure monitors applied to neonates and children are primarily developed from extension and modification of an empirically based fixed ratio algorithm used in adults. However because the fixed ratio algorithm does not count for patient specific arterial compliance and pressure waveform, the accuracy and reliability of the pressure measurement are still limited by variations of patient circulatory physiology from newborn infants to children. A key to addressing this problem is found in a physiologically based oscillometric method for noninvasive arterial pressure measurement, which utilizes patient specific physiological information (compliance and waveform) from the same oscillogram as measured by the current oscillometric devices. Since the new method will incorporate physiological variation with a pressure measurement algorithm, it follows that accuracy and reliability of blood pressure values should be increased in proportion to the decreased influence of the physiological variations. Since the new method uses the same oscillogram information as the current oscillometric devices to calculate pressure values, it is logical to develop a new algorithm based on the current device hardware and upgrade its software in order to achieve the benefit of the new method while retaining the advantages of hardware design and operation strategy for the current devices - therefore reducing the cost for the new product development. It is therefore proposed to test and verify the expected improvement in accuracy and reliability of pediatric pressure measurement by applying the physiologically based oscillometric method.